That being said, many are quick to dismiss them since they don't have the nicest/largest stores, or the most advanced systems. By doing so your ignoring reality, as that is how most people get their food, hence why they (generally) accept EBT.
In an urban market, these type of stores are 15,000-30,000 sqft. We have a few markets like this in my city, but they are in nicer areas.
Poor folk have corner stores that are <3000 sqft. We don't have the Asian produce markets or Mexican markets that you are thinking of. They generally don't sell produce, and if they do they low quality and 2x expensive.
We had a crisis about a decade ago because 80% of these stores were temporarily shut down after the owners were arrested for accepting food stamps for heroin. They aren't nice places that anyone chooses to do business with.
Most people there get food from a bodega type place.